Lost Channels

[wolsty]

I have a Hummie 5400z patched with ToH 2.3 and loaded with Xamuh's latest settings, PMC and ECM files. When tuned to S*y News and TCM on 28 degs E, I get a 'No or Bad Signal' message. There may be a similar problem with other channels on this satellite, but I'm not really interested in them. The problem has occurred since I upgraded my software a few weeks ago and is not a major annoyance: I'd just like to know why it's happened. Any suggestions?

[wolsty]

Now I'm really confused. I left my Hummie set on TCM and about an hour later, the channel suddenly cleared. So I did a bit of channel hopping and everything seemed to be there. Then they disappeared again. Half an hour later, they came back. What's going on?

[2old4this]

Perhaps you are tuning in to channels whose PIDs (or more) are periodically changing. Sky News is transmitted on many different transponders and PIDs at 28.2e, some of them clearly "tests" or duplicates.

Or perhaps it was sporadic bad weather?

Did you suffer any similar problems on other channels at the same times?

2old

[wolsty]

@ 2Old.
The problem ocuured after an upgrade, using all Xamuh's files. I don't use 28 degs much, since there's little of interest for me there except S*y News and TCM, so it hasn't worried me much. It's certainly not bad weather, as I have good signal strength and quality all the time.

Since I posted, I've left the STB tuned to TCM overnight and there's no problem - the picture was still clearing this morning. However, a few minutes ago I moved the dish to 19 deg E and tuned in to a few channels, then back to S*y News on 28 degs and I got the message 'No or Bad Signal' again. All channels seem to be affected, including TCM.

I don't understand workings of PID's, ECM's etc, but my layman's guess is that this is where the problem lies, as until I changed the settings/ECM's/PMC's I'd never had a problem. As I said above, it's not very important, but I would lilke to learn something from the situation.

[wolsty]

The problem (ie 'No or Bad Signal') also occurs on French C+ channels.

[2old4this]

you mentioned it's ocurring on TCM & Sky News at 28e - well they are FTA, so there shouldn't be any problem with ECMs.
I'm wondering whether it might be a tuner fault on your receiver, or an LNB/cabling problem.

Just check one thing for me - check the polarity of all the channels that this is happening on. Often when an LNB fails, it fails on one polarity only. If the dicky channels are either all H or all V then try a different LNB. In fact you might like try a different LNB anyway. If you know a local sat dealer s/he might be willing to let you test your receiver on a dish in the shop.

2old

[wolsty]

@ 2old. Hmm. Very interesting! The LNB is only a couple of months old; I bought it from Channel Hopper. It's worked well to date. I've just checked the polarisation of the channels concerned. All the 28 deg ones I was interested in are vertical, as are the French C+. However, the idea comes unstuck on 1 deg W. Kiosk 1 - 11 are horizontal (very weak signal where I live, but clears during daylight or when there is no cloud/rain). 12 - 22 are vertical and I've never had any difficulty with them.

BUT, the problem seems to have gone away. I've left the receiver switched on permanently, first swithced to S*y, then to C+ - so each channel has been locked on for some time. Both 28 deg and C+ now clear reliably as soon as I switch to them.

Is it the case that various parameters are updated automatically and that by leaving the STB 'on soak' on one of the affected channels the various settings have automatically updated?

[2old4this]

Not aware of any such effect. The PIDs and other identifiers that your tuner needs to extract from the bitstream in order to "lock onto" the channel come in within seconds, and unless the priovider is for some reason buggering about with them they should stay constant. Leaving the receiver tuned in for a day longer won't make any difference.

If you now turn off your tuner and let it go cold, then turn on gain, is all still hunkydorey?

2old

[wolsty]

@ 2Old.

C+ and S*y/TCM have gone again. After an afternoon of working perfectly, the both ceased to clear. But I think you were on the right track with polarisation, as I've just done a more systematic check. All the channels which return a 'No or Bad Signal' message are vertically polarised; no horizontally polarised channel does this (except for those which are too weak for me to receive). However, some vertically polarised channels do clear - notably Kiosk 11-22 and odd channels on other satellites, eg Superpippa. I'll check the switching off/cooling down situation and let you know how I get on.

[Channel Hopper]

Ill send down another LNB if you get a reoccurrence when its back on after the cool down

Never heard of it before though, it may possibly be a power supply problem causing a low voltage on one polarity, or extra corrosion on the outer F plug

Is it a long run of cable to the dish ?

[wolsty]

Thanks Channel Hopper. That's very generous of you.

I let the receiver cool down last night, but when I tried this morning, Sky News and C+ had disappeared again. I left the STB switched to Sky News and went out for the day. On my return, I switched on the TV set and guess what. Sky News had cleared. So did the other channels. I've channel hopped to my heart's content for the last half hour or so and the problem hasn't recurred.

Could it be the skew setting? Would the problem ameliorate if I rotated the LNB slightly?

Corrosion on the plug is a possibility and yes, it's a long cable run. What should the voltages be? I'll check when it stops raining.

Why does the problem occur on only some V polarised channels?

[2old4this]

could conceivably be skew though that would be more likely to affect both H and V.

Why only some V channels?

Well often one or other is the stronger signal. Here I can receive the V transponders on Nilesat with no problem but the H only with difficulty
Also the strengths of individual transponders vary. The weaker ones will be the fiorst to go if your reception is marginal. You might also find that weaker signals only come in at certain times of the day/year when atmospheric absorption & scattering (by moisture and/or dust) is less.

When you recover reception, how strong is the signal (and quality)? How does it compare to transponders on whihc you have no such problems?

TYpically signal strength and quality should be upwards of 70% for Astra & Hotbird in Europe. If quality drops to about 30% you'll start to lose reception.

2old

[Channel Hopper]

Ive got a funny feeling the problem is voltage related

There may be a null region that the receiver does not pass through during the switch from horizontal (18V) to Vertical (14V)

Rather than switching off and letting the receiver change state, can youtry disconnecting the LNB cable momentarily, and then looking for the lost channels. Temporarily connecting a Line amplifier (or even a DiSEqC switch) drops the voltage by about 0.7V along the cable, which may give a clue as to whats going on

[wolsty]

Well, well! I just stumbled across this thread on the Dudez:

http://www.satdudez-forumz.com/forum...&threadid=2492

Seems as if I'm not the only one!

[Channel Hopper]

My word, theres a second Wolsty asking exactly the same question on that site.

Parallel universe ?

[wolsty]

@ Channel Hopper. One wolsty per universe is enough. Or so my wife tells me. Perhaps in a parallel universe polarities are reversed and it's the H channels which pose the problem.

Which reminds me.

I've tested a few voltages and signal strengths. The STB produces a voltage of 14.3 for all H channels tested and 18.6 for the V channels tested. Signal strength, quality and polarisation are, respectively:
28 deg E Sky News: 49%, 91% V;
28 deg E TCM: 49%, 57% V;
Hotbird Superpippa: 46%, 87% V;
Hotbird Multivision 1: 42%, 60% V;
19 deg E Premiere 1: 49%, 56% H;
19 deg Direkt Portal 47%, 52% H.

Despite the relatively low signal strengths (I am in the far SW, after all), all the above channels have cleared reliably ever since I've had the Hummie, with the notable exception of those from Sky News, TCM, French C+ etc which, as mentioned previously have given the 'No or Bad Signal' message only within the last few months.

I still don't understand why, if the receiver is left switched to the problem channel for a long time, the signal clears and reception is then faultless.

[wolsty]

And there's more. Having left the receiver tuned to Direkt whilst I typed the last message, I then tuned to french C+. 'No or Bad Signal' message again. Checked voltage. 14.19. So it seems that the problem is in the LNB or cabling.

[rolfw]

Have you got those voltages reversed Wolsty? I believe that the Higher voltage should be for horizontal and the lower Vertical.

[wolsty]

Doh! You're right Rolf.

[Channel Hopper]

Did you keep or bin the old LNB ?

You could try turning the LNB 90 degrees and see if a reversal of
polarity in the channel search brings the programmes back again

I will send another LNB out to you tomorrow regardless

[wolsty]

@ Channel Hopper.

Of course I kept the old one! Much to my wife's chagrin, I never throw anything away. I'll try the tweak, as you suggest, but thanks for the promise of a new LNB. I'm not going anywhere near the roof today - it's raining hard. Maybe tomorrow.

I've just noticed that if I switch from an H channel, eg Reality TV, to a V channel, eg Sky News, the signal sometimes clears for a brief time (0.5 seconds or so) then disappears - like when automatic tuning 'overshoots' the station. So I still wonder if adjusting the skew will do the trick. Remember that I have no problems with satellites close to due S, but the Astras, which are more degrees off, give most of the bad signal responses.

[satoons]

I noticed today that the adult channel X ZONE is no longer available including some other channels.
have they moved to SECA 2?

[Channel Hopper]

Off thread but yes its gone over to the dark side, following Canal + 16/9 a couple of weeks ago

[wolsty]

Replacement LNB cured the problem. Thanks Channel Hopper.